FROM JOHN SASSO, LESSONS ON DEFEAT AND JESSE JACKSON

While the attention of the nation was focused on Washington and the inauguration of President Bush, the architect of the losing 1988 campaign unburdened himself of some thoughts up in Boston. John Sasso offered a few important lessons for the Democratic Party-especially on the subject of Jesse Jackson.

Sasso was Michael Dukakis` top aide from 1980 onward and the man who shaped the basic blueprint Dukakis used in capturing the Democratic presidential nomination. Before the first primary, Sasso was exiled for his part in undermining the rival candidacy of Sen. Joseph Biden Jr. But after Dukakis squandered his early lead, he brought Sasso back for the rescue effort in the final two months.

His speech last week departed from the long tradition of insiders` post-mortems on failed presidential efforts in being short on self-serving alibis and parting shots at rivals on his own team.

He acknowledged mistakes for which no one but Dukakis and his aides were responsible: the parochialism of the Dukakis hierarchy, the failure to establish a clear campaign theme and a compelling case for political change and the inattention to issues like crime and defense that touch on national values.

While decrying the ''negative, distorting'' ads Bush used against the Democratic nominee and faulting the press (justifiably) for its tardiness and reluctance to play ''truth squad'' on campaign ads, Sasso said Democrats should recognize ''our own lack of a central and sustained theme created the vacuum . . . that allowed flags and furloughs to dominate.''

Those appeals touched voters in ways that were incomprehensible to the people in Dukakis` Boston headquarters, because Sasso`s successors assembled a campaign team of remarkable cultural and political insularity. While Cambridge and Boston dominated the Dukakis circle, Bush`s team included people experienced in national campaigns and reared in Texas and South Carolina, barometers of the South, and the key states of California, Ohio, Michigan, New Jersey-and Massachusetts.

''Only by having a feel for the entire country,'' Sasso said, ''can a campaign come up with the kind of insights and strategy-day by day and even hour by hour-that are essential to . . . winning.''

Few Democrats will disagree with Sasso on those points, but what he said about Jackson will surely stir a debate. ''After two elections . . . of watching Walter Mondale and Mike Dukakis strain to . . . develop some kind of solid political relationship with Jesse Jackson, only to see that relationship turn tense and even adversarial,'' Sasso said, ''I think it is imperative that Democratic leaders, including Jesse Jackson, together decide to do things a hell of a lot better.''

Sasso came to see Jackson as a man who ''holds very fixed views-always important for a strong leader-and has a very exact ideological approach. Often, when he disagrees, he tends to see the differences in racial terms.''

In dealing with such a man, Sasso said, the policy of turning the other cheek, practiced by both Mondale and Dukakis, has high costs. It was ''a mistake on our part. Covering up sharp disagreements . . . was corrosive and draining. . . . Jesse Jackson himself says he wants to be treated as other political leaders are treated. He is right. He should be and he is not.''

One reason, unacknowledged by Sasso, is that Jackson so easily dominates other politicians physically and psychologically when he is with them. But the other factor is liberal guilt. ''The weight of historical injustice makes it extremely difficult for a Democratic candidate in any way to diminish Jackson, for the candidate seems at the same time to be criticizing a whole community who believe Jackson is the only leader who really stands up and fights for them,'' Sasso said.

Blacks are the Democrats` most loyal voting bloc. Sasso is right in saying that the way for future Democratic candidates to acknowledge their debt to that community is not to stifle their disagreements with Jackson, but to

''build bridges of their own . . . by campaigning vigorously in black communities.''

''This is not to challenge Jesse Jackson,'' he said, a bit disingenuously. ''It is to challenge black voters.''

Sasso`s advice is also a challenge to all those who would contest with Jackson for leadership of the Democratic Party in the next four years. From beginning to end, his speech is a major contribution to the Democrats`